Mobile terminals, such as cellular phones, smart phones and tablet terminals, typically include a battery or a similar electric power storage device, and respective devices installed in the mobile terminals operate on electric power received from the electric power storage device.
One issue to be addressed in the design of a mobile terminal is that the electric power supply from the electric power storage device may be suddenly stopped. The most typical example in which the electric power supply from the electric power storage device is suddenly stopped is the case when the electric power storage device is removed from the mobile terminal by a user. Many mobile terminals are designed such that the battery is replaceable by the user and, in such a design, the user may remove the battery from the mobile terminal. Even in the case when the mobile terminal is designed so that the battery cannot be easily removed by the user, the battery may be removed in the product inspection by an inspector.
When the power supply from the electric power storage device is suddenly stopped, the system becomes unable to continue the operation and an abnormal shutdown occurs. It is desired that a mobile terminal is designed so that, even when a sudden break of the electric power supply from the electric power storage device causes an abnormal shutdown, the abnormal shutdown does not cause a malfunction.
In general, a mobile terminal includes a panel display device such as a liquid crystal display device and it would be therefore desirable that a panel display device does not suffer from a malfunction even when an abnormal shutdown occurs. Under such a background, the inventor has studied suppression of malfunctions of a panel display device when an abnormal shutdown occurs.
One malfunction studied by the inventor is occurrence of an abnormal display on the panel display device. When an abnormal shutdown occurs due to a stop of the electric power supply from the electric power storage device, the operation of the system is stopped in a situation in which charges remain in the display panel of the panel display device and this may result in that an abnormal display appears on the display panel. In general, when the system is normally shut down, the operation of the system is stopped after the charges remaining in the display panel are discharged and the abnormal display on the display panel is thereby avoided. When an abnormal shutdown occurs due to a stop of the power supply from the electric power storage device, however, it is difficult to avoid the abnormal display onto the display panel by carrying out the same operation as the case when the system is normally shut down.
From such a background, it is desirable if a technique is provided which suppresses occurrence of an abnormal display on a display device in the case when an abnormal shutdown occurs due to a stop of the electric power supply.